Source
https://ir.canterbury.ac.nz/items/86841ceb-c5bf-46e7-888b-860e141568f3 — original source (opens in a new tab; the file is not redistributed)
Miller et al. (2015) — Economics of Photovoltaic Solar Power and Uptake in New Zealand
GREEN Grid / EPECentre (University of Canterbury) techno-economic study of NZ solar PV at three scales — residential rooftop (2 & 3.5 kWp), commercial rooftop (50 kWp) and ground-mount utility (2 MW) — using discounted cash-flow NPV and LCOE. Its durable value to Neobiome Intelligence is a regional half-hourly PV capacity-factor set (NIWA TMY irradiance, fixed 30° north tilt: 0.128 Otago/Southland → 0.174 Nelson, Canterbury/Christchurch 0.151) and eight clustered half-hourly Christchurch residential load shapes (annual use 3,162–15,102 kWh) — exactly the NZ demand-side + supply-side inputs a recalibration of the Afzalan community-self-sufficiency method would need. ⚠ It advances but does not resolve RT_172: it never computes a self-consumption / community self-sufficiency ratio or a complementarity factor. ⚠ 2015 vintage — the PV cost inputs (
3.5/W residential →2.0/W utility) and the NPV/LCOE outputs are badly cost-dated (PV has since fallen ~70%); use the capacity factors and load-shape taxonomy, not the 2015 costs.
Summary
This EEA 2015 conference paper (part of the GREEN Grid research programme at the University of Canterbury’s EPECentre) assesses the commercial attractiveness of solar PV to NZ investors at three scales — residential rooftop, commercial rooftop and utility ground-mount — using discounted cash-flow net present value (NPV) to judge investment viability and levelized cost of energy (LCOE) to compare PV against other generation. PV generation is modelled from NIWA typical-meteorological-year irradiance (Perez diffuse transposition, 30° tilt, north azimuth), giving region-specific capacity factors. For the residential case, more than 2,000 Christchurch half-hourly load profiles were clustered into eight representative house types (by user size, tariff, space-/water-heating and daytime occupancy), each carried at half-hourly (17,520-period) resolution, because the value of PV to a household turns on how much generation is self-consumed at the retail rate versus exported at the much lower 8 c/kWh buy-back rate.
The headline findings: PV was (in 2015, at the assumed costs) commercially attractive only for some household types — large users, and low users with electric hot water not on a night-rate tariff — and even then only for householders with ready access to finance who seek low-risk investments; returns are very sensitive to discount rate, location and retail-tariff structure. Commercial PV is attractive in some cases (high all-day daytime load, e.g. malls/supermarkets). Utility PV has the lowest LCOE of the three scales but is not commercially attractive (every regional NPV is negative), because utility output sells at the spot price rather than displacing a retail rate. Across all scales the authors note that improving energy efficiency (from 0 c/kWh) is a lower-cost option than PV and should be considered first, and that much of the household “saving” from PV is really the avoidance of variable charges that recover fixed network costs — so it does not necessarily represent a true saving to the nation. This is context: ni: the load-bearing value is the NZ-calibrated capacity-factor set, the residential load-shape taxonomy, and the NZ PV LCOE envelope by scale.
Key claims
- claim: "NZ installed PV grew from about 7 MW at end-2013 to 20.2 MW at February 2015. At February 2015 total NZ PV was 20.249 MW, of which 91% was in systems ≤10 kW (assumed residential) and 9% in systems >10 kW (assumed commercial), i.e. 4.5 watts per person nationally. Commercial cumulative installed capacity had grown ~12% per month over the prior six months (highest rate since the Electricity Authority began collecting statistics in August 2013), while residential cumulative-capacity growth slowed from ~12% (Feb 2014) to 6% (Feb 2015), attributed to the November 2014 cut in buy-back rates."
source_location: "Section 1 Introduction, p.3 (7 MW → 20.2 MW; 12%/month commercial; 12%→6% residential); Table 1, p.5 (20.249 MW, 91%/9%, 4.5 W/person)"
- claim: "Regional PV penetration in watts-per-person (Table 1, Feb 2015) was led overwhelmingly by the top of the South Island: Tasman 18.5, Nelson 12.7, Marlborough 10.6, then Hawke's Bay 6.9, Otago 6.8, Northland 6.3, Southland 6.1, Canterbury 5.6, Bay of Plenty 4.3, Waikato 4.2, Taranaki 3.9, Auckland 3.8, Gisborne 3.1, Manawatu-Wanganui 2.3, Wellington 1.8, West Coast 1.5. By total capacity Auckland (5.817 MW) and Canterbury (3.191 MW) dominate. The context is the NZ government target of 90% of electricity from renewable sources by 2025."
source_location: "Table 1, p.5 (watts-per-person + total MW columns); Abstract, p.1 (90%-by-2025 target)"
- claim: "Modelling assumptions (Table 2): system sizes residential 2 kWp and 3.5 kWp, commercial 50 kWp, utility 2,000 kWp (2 MW). System capital cost $3.5/W (2 kWp residential), $3.0/W (3.5 kWp residential), $2.5/W (commercial), $2.0/W (utility). Inverter replacement after 15 years $0.4/W (residential & commercial), 0 (utility). O&M $20/kW/year escalating at 2%/yr; balance-of-system losses 4%; annual panel degradation 0.8%/yr; panel tilt 30°, azimuth 0° (north); no temperature effects; salvage value 0. Neither land value nor opportunity cost of roof/land use is included. Analysis period 25 years."
source_location: "Table 2, p.5 + footnote (1)"
- claim: "Price and financial assumptions (Table 2): residential grid buy-back rate 8 c/kWh (Contact Energy); residential variable retail (Contact Energy Christchurch) — low-user flat 25.395, low-user day/night 29.022, high-user flat 23.462, high-user day/night 27.089 c/kWh; commercial variable retail range 10, 12 and 14 c/kWh; utility sells all output at spot price (2010–2014 series repeated and escalated). Electricity PPI annual adjustment 1.5%/yr. Discount rates: residential 4%, 7% and 20%; commercial 6% and 8%; utility 6%. Corporate tax 28% with straight-line depreciation tax shield for commercial and utility only."
source_location: "Table 2, p.5 (buy-back, retail, discount rates, tax) + footnotes (3)(4)(5)(6)"
- claim: "Residential load taxonomy: more than 2,000 Christchurch half-hourly load profiles were clustered by (1) low- vs high-user (low user <9,000 kWh/annum), (2) tariff (flat vs day/night), (3) winter-vs-summer consumption (electric space heating), (4) daytime (10am–4pm) occupancy, (5) morning-peak (8–10am) consumption (electric water heating). Eight representative categories were selected, representing 85% of profiles (1,880 of the sample), with the median taken across all 17,520 half-hours of the year. Annual consumptions by house type: Type 1 = 3,162 kWh; Type 2 = 4,078; Type 3 = 5,878; Type 4 = 4,475; Type 5 = 9,843; Type 6 = 9,969; Type 7 = 13,174; Type 8 = 15,102 kWh."
source_location: "Section 3 Residential Returns, p.6 (>2,000 profiles, 85%, 17,520 half-hours); Table 3, p.7 (8 house types, annual kWh, sample counts)"
- claim: "Residential NPVs and LCOE for Christchurch (Table 4, capacity factor 0.151). NPV rises steeply with daytime/large load and falls with discount rate. For the 3.5 kWp $3.0/W system: House Type 8 (15,102 kWh) NPV +$6,829 (4%), +$2,667 (7%), −$4,398 (20%); Type 7 +$4,175 / +$659 / −$5,314; Type 1 (3,162 kWh) −$1,030 / −$3,294 / −$7,139. Residential LCOE (3.5 kWp) = 16.9 c/kWh (4%), 21.2 (7%), 41.0 (20%); LCOE (2.0 kWp $3.5/W) = 19.4 / 24.4 / 47.6 c/kWh. PV is commercially attractive (positive NPV) mainly for large users and low users with electric hot water not on night-rate tariffs, and only at low discount rates (financed, low-risk households)."
source_location: "Table 4, p.7 (NPV grid + LCOE row, CF=0.151); Discussion §6, p.9–10"
- claim: "Commercial returns for a 50 kWp system with business load above 50 kW most days (Table 5). At a 6% discount rate, regional NPV is positive only at the 14 c/kWh retail rate in higher-irradiance/higher-value regions (e.g. Nelson +$12,487, Taranaki +$7,716, Auckland +$2,546) and negative elsewhere; at 10 c/kWh every region is negative. Commercial LCOE ranges 14.6–19.8 c/kWh (6%) and 17.2–23.4 c/kWh (8%), lowest at Nelson (14.6 / 17.2) and highest at Otago (19.8 / 23.4)."
source_location: "Table 5, p.8 (NPV by region × retail rate; LCOE columns for 6% and 8%)"
- claim: "Utility-scale (2 MW) results (Table 6): every regional NPV is negative at both 6% and 8% discount rates — utility PV is the least commercially attractive scale despite having the lowest LCOE, because all output is sold at the spot price (below residential/commercial retail rates), and transmission/distribution charges are excluded (their inclusion would make it even less attractive). Utility LCOE ranges 10.7–14.6 c/kWh (6%) and 12.8–17.4 c/kWh (8%): lowest at Nelson (10.7 / 12.8), highest at Otago (14.6 / 17.4). Most-negative NPV is Otago (−$1,848,341 at 6%)."
source_location: "Table 6, p.9 (NPV + LCOE by region); Section 5 Utility PV Returns, p.9; Discussion §6, p.10"
- claim: "Region-specific PV capacity factors (fixed 30° north tilt, NIWA typical-meteorological-year irradiance, Perez diffuse transposition, no tracking, no temperature derate), identical across the commercial (Table 5) and utility (Table 6) analyses: Nelson 0.174 (highest), Taranaki 0.168, Auckland 0.161, Bay of Plenty 0.161, Waikato 0.155, Manawatu 0.155, Wellington 0.155, Canterbury 0.151, West Coast 0.149, Otago 0.128 and Southland 0.128 (lowest). Christchurch residential is 0.151 (= Canterbury). Nelson and Tasman have the highest irradiation; Taranaki, Auckland and Northland have slightly lower irradiation but higher spot prices."
source_location: "Table 5, p.8 (Capacity Factor column); Table 6, p.9 (Capacity Factor column); Table 4 caption, p.7 (Christchurch 0.151); Discussion §6, p.10"
- claim: "Cross-technology LCOE comparison (Figure 2, drawing on Lazard's Levelized Cost of Energy v8.0, 2014): geothermal ~8–14 c/kWh and wind ~4–11 c/kWh are still more commercially attractive than PV in New Zealand, and energy efficiency 'starts at 0 c/kWh' — so before even considering PV, one should consider energy efficiency. Utility-scale PV has the lowest LCOE of the three PV scales (due to its lower per-watt costs)."
source_location: "Section 6.1 Comparisons, p.10; Figure 2, p.10"
- claim: "Structural / national-benefit conclusions: household load shape is the major driver of residential PV value (returns hinge on how much generation is self-consumed at the retail rate vs exported at the 8 c/kWh buy-back). Previous GREEN Grid work found PV has little ability to reduce the system peak (a winter evening peak), compounded by less PV generation on the coldest days, and does not increase supply reliability — implying little ability to reduce transmission/distribution costs. Consequently much of the consumer 'saving' from PV arises from avoiding variable charges that recover the fixed costs of the distribution/transmission network, and does not necessarily reflect a real cost saving to the nation; the national benefit is likely lower than the investor-level analysis suggests."
source_location: "Discussion §6 + Conclusion, p.9–11 (load-shape driver, GREEN Grid peak/reliability finding, variable-charge caveat); Abstract, p.1–2"Neobiome Intelligence relevance
This is the RT_172 candidate. It feeds D01 (renewable energy & storage / energy economics) and its value is three-fold — with one strong vintage caveat.
- NZ regional PV capacity-factor set (D01 — the RT_172 supply-side input). The half-hourly, NIWA-TMY-derived, fixed-30°-north capacity factors — 0.128 (Otago/Southland) → 0.174 (Nelson), Canterbury/Christchurch 0.151 — are a clean, citable NZ recalibration set for the energy model’s PV yield term. They sit at the lower, no-tracking end of the utility/tracking envelope in OT_056 (0.12–0.20), which is exactly right for community fixed-tilt rooftop, and they corroborate the regional ordering in RD_013 (Nelson/Tasman best, Otago/Southland lowest). Because they are irradiance-driven, they are not compromised by the paper’s 2015 vintage.
- Eight clustered Christchurch half-hourly residential load shapes (D01 — the RT_172 demand-side input). The eight house types (annual use 3,162–15,102 kWh, differentiated by user size, tariff, electric space/water heating and daytime occupancy), each carried at 17,520 half-hourly points, are the demand side of a self-consumption calculation. Together with the capacity factors they are precisely the NZ analogue of the Austin 15-min load+PV inputs LIT_034 uses — so this document supplies the ingredients for an NZ recalibration even though it does not itself compute the ratio. Note the newer, larger EECA half-hourly datasets already in the corpus (OT_076 ~49,385 ICPs, 4 cities; OT_104) partly supersede this 2015 Christchurch-only basis.
- NZ PV LCOE envelope by scale (D01). Utility 10.7–14.6 c/kWh (6%), residential 16.9–24.4 c/kWh (excluding the 20%-discount outliers), commercial 14.6–19.8 c/kWh (6%) — a scale-ordered NZ PV LCOE envelope, plus the finding that geothermal (8–14 c/kWh) and wind (4–11 c/kWh) undercut NZ PV and that energy efficiency (0 c/kWh) beats PV and should come first — a useful ordering principle for a community-design tool.
⚠ Cost-vintage caveat (load-bearing). The PV system costs (3.5/W and 3.0/W residential, 2.5/W commercial, 2.0/W utility) and therefore every NPV and LCOE are ~10 years stale — NZ PV has fallen roughly 70% since 2015 (current community-scale ≈ $1,600/kWp per CR_024; residential price surveys URL_010). Do not enter the 2015 cost/NPV/LCOE numbers into any current cost cell — today’s economics are materially better than this paper’s “attractive only for financed low-risk households” conclusion. Also note the 8 c/kWh buy-back and the Christchurch-only retail rates are 2015 Contact Energy figures (superseded by CR_022).
Scope note (self-sufficiency framing). The RT that sought this document is framed around the Afzalan community complementarity factor and self-sufficiency ratio. This paper computes neither — it is an investor-return study (NPV/LCOE), not a self-sufficiency study. Its contribution is the NZ-calibrated inputs, not the outputs; the residual gap (an actual NZ self-consumption / community self-sufficiency benchmark) survives.
Research targets
Advanced (not resolved)
- RT_172 (ADVANCED / PARTIAL → this page): the target sought a national NZ PV self-consumption / community self-sufficiency benchmark at sub-hourly resolution to recalibrate the Afzalan CF and self-sufficiency formulas. This paper delivers the recalibration inputs — regional half-hourly PV capacity factors (0.128–0.174) and eight clustered half-hourly Christchurch residential load shapes — but does not compute a self-consumption ratio, a community self-sufficiency ratio, or a complementarity factor. The residual gap remains open: an NZ source that actually reports the self-consumption / self-sufficiency benchmark (or an NI-internal computation from these inputs + the EECA half-hourly profiles OT_076 / OT_104). RT_172 therefore stays open; the demand-side (Christchurch-only) and the missing self-sufficiency output are the residuals.
Notes
Single-file raw — a 20-page EEA Conference & Exhibition 2015 paper (Wellington, 24–26 June 2015) from the University of Canterbury EPECentre under the GREEN Grid research programme (funded by MBIE, Transpower, the EEA and UC; Meridian Energy supplied the residential load profiles). Read verbatim via pdftotext -layout; every quantitative claim is traceable to a numbered table, section or footnote → data_quality: verified.
⚠ 2015 cost vintage (repeated because it is the main risk). The system-cost inputs and all NPV/LCOE outputs are ~10 years stale and far above current NZ PV prices — the capacity factors and load-shape taxonomy are the durable, still-valid content; the cost/return figures are historical context only. This is the same “component/model outputs, not current outturn” caveat that applies to the sibling NZ energy-economics studies in the corpus.
⚠ Two different “CF”s — do not conflate. In this paper “CF” (or “capacity factor”) is the PV yield ratio (0.128–0.174). In the RT_172 parent LIT_034, “CF” is the complementarity factor (community surplus ÷ deficit). RT_172 asked to recalibrate Afzalan’s complementarity/self-sufficiency metrics; this paper supplies capacity factors and load shapes, not a complementarity factor — hence RT_172 is advanced, not resolved.
⚠ Distinct from OT_056. This is Miller et al. 2015 (EEA conference paper; residential + commercial + utility PV investor economics). OT_056 is Miller 2020 (a later MBIE consulting report, utility-scale only, single-axis tracking). Same lead author, different documents, non-overlapping cost bases — not a duplicate.
Connections
Links to
Referenced by
EDT domains (1): D01: Renewable Energy & Storage Systems
Sources (1): LIT_084